Light source device and display device

ABSTRACT

There is provided a light source device including a first light source configured to emit light in a first wavelength region, a second light source configured to emit light in a second wavelength region different from the first wavelength region, a wavelength conversion unit including a fluorescent material and configured to emit fluorescent emission light in a different wavelength region upon irradiation with the light in the first wavelength region, and a combining unit that has wavelength selectivity to a specific wavelength region corresponding to the second wavelength region and combines the light in the first wavelength region from the first light source, the light in the second wavelength region from the second light source, and the fluorescent emission light which are incident on the combining unit with one another.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 14/205,401, filed Mar. 12, 2014, which claims thebenefit of priority from prior Japanese Priority Patent Application JP2013-060060 filed Mar. 22, 2013, the entire contents of which areincorporated herein by reference. Each of the above-referencedapplications is hereby incorporated herein by reference in its entirety.

BACKGROUND

The present disclosure relates to a light source device used for adisplay device such as a projector and a display device including thesame.

A light source for a projector mainly employs an extra-high pressuremercury lamp in view of brightness and cost performance, and meanwhile,a solid-state light source, which has long service life and wide colorgamut, has attention in view of the long service life and additionalhigh functions. The solid-state light source is a light source utilizinglight emission from a p-n junction of semiconductor, such as an LED anda laser diode (LD). Recently, for example, as in JP 2012-27052A, a lightsource device is used for a projector in which device the solid-statelight source irradiates, with light, a fluorescent material which isirradiated with the light in a specific wavelength region to emit lightin a different wavelength region and the resulting fluorescent emissionlight is utilized.

For example, FIG. 9 represents a transmission-type light source device10A for collecting light emitted from a first light source 11 on atransmission member 14 a such as glass on which a fluorescent material13 is provided using a lens 12 and outputting the light having passedthrough the transmission member 14 a to be parallel light using a lens15. FIG. 10 represents a reflection-type light source device 10B forcollecting light emitted from the first light source 11 on a reflectionmember 14 d on which the fluorescent material 13 is provided using alens 17 and reflecting the light reflected by the reflection member 14 dwith a dichroic mirror 16 to be outputted.

Such light source devices using a fluorescent material have a merit oflong service life compared with an existing high pressure mercury lampused for a projector. Usage of a fluorescent material can also reducespeckle noise of glistening spots on the surface of the irradiatedobject.

SUMMARY

Meanwhile, a fluorescent material with an emission spectrum suitable fora projector has not yet been put into practical use in fact.

A light source for a projector is desirable to present the standardizedcolor gamut and white for a video display device based on the DCIstandard or the sRGB standard as illustrated in FIG. 11. In order topresent such color gamut, ideal one is a light source with emissionspectra for the blue wavelength region, the green wavelength region andthe red wavelength region as illustrated in FIG. 12. Such a light sourcewith the emission spectra can present colors close to those in thestandard for the primary colors of red, green and blue and for white inpresenting the primary colors at the same time.

Methods for realizing the spectra using fluorescent substances include amethod of using a mixture of fluorescent substances with the individualemission spectra. For example, as illustrated in FIG. 13, a mixture of afluorescent substance A having the blue light emission wavelengthregion, a fluorescent substance B having the green light emissionwavelength region and a fluorescent substance C having the red lightemission wavelength region is used. The light emission of fluorescentsubstances, however, suffers luminance saturation and temperaturequenching, these meaning the strong light which is incident on thefluorescent substances to cause a decrease of the fluorescent lightemission efficiency as illustrated in FIG. 14. Therefore, thefluorescent substances low in light emission efficiency do not promise alight source bright and excellent in efficiency.

It is desirable to attain a light source device high in efficiency andexcellent in color reproducibility.

According to an embodiment of the present disclosure, there is provideda light source device including a first light source configured to emitlight in a first wavelength region, a second light source configured toemit light in a second wavelength region different from the firstwavelength region, a wavelength conversion unit including a fluorescentmaterial and configured to emit fluorescent emission light in adifferent wavelength region upon irradiation with the light in the firstwavelength region, and a combining unit that has wavelength selectivityto a specific wavelength region corresponding to the second wavelengthregion and combines the light in the first wavelength region from thefirst light source, the light in the second wavelength region from thesecond light source, and the fluorescent emission light which areincident on the combining unit with one another.

According to an embodiment of the present disclosure, there is provideda light source device including a first light source configured to emitlight in a first wavelength region, a second light source configured toemit light in a second wavelength region different from the firstwavelength region, a wavelength conversion unit including a fluorescentmaterial and configured to emit fluorescent emission light in adifferent wavelength region upon irradiation with the light in the firstwavelength region, and a combining unit that has wavelength selectivityto a specific wavelength region corresponding to the first wavelengthregion and the second wavelength region and combines the light in thefirst wavelength region from the first light source, the light in thesecond wavelength region from the second light source, and thefluorescent emission light which are incident on the combining unit withone another.

According to an embodiment of the present disclosure, there is provideda display device including a light source unit, a lightmodulating/combining system configured to modulate and combine incidentlight, an illumination optical system configured to guide light emittedfrom the light source unit to the light modulating/combining system, anda projection optical system configured to perform projection of an imageemitted from the light modulating/combining system. The light sourceunit includes a first light source configured to emit light in a firstwavelength region, a second light source configured to emit light in asecond wavelength region different from the first wavelength region, awavelength conversion unit including a fluorescent material andconfigured to emit fluorescent emission light in a different wavelengthregion upon irradiation with the light in the first wavelength region,and a combining unit that has wavelength selectivity to a specificwavelength region corresponding to the second wavelength region andcombines the light in the first wavelength region from the first lightsource, the light in the second wavelength region from the second lightsource, and the fluorescent emission light which are incident on thecombining unit with one another.

According to an embodiment of the present disclosure, there is provideda display device including a light source unit, a lightmodulating/combining system configured to modulate and combine incidentlight, an illumination optical system configured to guide light emittedfrom the light source unit to the light modulating/combining system, anda projection optical system configured to perform projection of an imageemitted from the light modulating/combining system. The light sourceunit includes a first light source configured to emit light in a firstwavelength region, a second light source configured to emit light in asecond wavelength region different from the first wavelength region, awavelength conversion unit including a fluorescent material andconfigured to emit fluorescent emission light in a different wavelengthregion upon irradiation with the light in the first wavelength region,and a combining unit that has wavelength selectivity to a specificwavelength region corresponding to the first wavelength region and thesecond wavelength region and combines the light in the first wavelengthregion from the first light source, the light in the second wavelengthregion from the second light source, and the fluorescent emission lightwhich are incident on the combining unit with one another.

According to an embodiment of the present disclosure, the wavelengthconversion unit combines the fluorescent emission light obtained byconversion of the light in the first wavelength region, the light in thefirst wavelength region from the first light source, and the light inthe second wavelength region from the second light source with oneanother on a same axis. The combined light has the wavelength spectra ofthe first wavelength region, the second wavelength region and thefluorescent emission light. Thereby, the light in the first wavelengthregion from the first light source and the fluorescent emission light,which have a deficiency in their emission spectra, can be effectivelysupplemented with the light in the second wavelength region using thesecond light source.

As described above, according to the present disclosure, a light sourcedevice high in efficiency and excellent in color reproducibility can beattained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic configuration diagram illustrating one exemplaryconfiguration of a display device including a light source unitaccording to a first embodiment of the present disclosure;

FIG. 2 is a graph illustrating a representative emission spectrum of aYAG-based fluorescent material and a spectrum of excited light;

FIG. 3 is a schematic configuration diagram illustrating a configurationof the light source unit according to the embodiment;

FIG. 4 is a graph illustrating one example of a wavelength spectrum fora laser emitting light in the red wavelength region;

FIG. 5 is an explanatory drawing illustrating one example ofcharacteristics of a second dichroic mirror;

FIG. 6 is an explanatory drawing illustrating one example of awavelength spectrum of light emitted from the light source unitaccording to the embodiment;

FIG. 7 is a schematic configuration diagram illustrating a configurationof a light source unit according to a second embodiment of the presentdisclosure;

FIG. 8 is an explanatory drawing illustrating one example ofcharacteristics of a dichroic mirror according to the embodiment;

FIG. 9 is an explanatory drawing illustrating one example of atransmission-type light source device according to the related art tothe present technology;

FIG. 10 is an explanatory drawing illustrating one example of areflection-type light source device according to the related art to thepresent technology;

FIG. 11 is a graph illustrating an xy chromaticity chart in the XYZcolor system and the color gamuts in DCI and sRGB;

FIG. 12 is an explanatory drawing illustrating an example of idealemission spectra of a light source;

FIG. 13 is an explanatory drawing of a concept of mixing a plurality offluorescent substances; and

FIG. 14 is an explanatory drawing of a decrease of fluorescent lightemission efficiency caused by luminance saturation and temperaturequenching.

DETAILED DESCRIPTION OF THE EMBODIMENT(S)

Hereinafter, preferred embodiments of the present disclosure will bedescribed in detail with reference to the appended drawings. Note that,in this specification and the appended drawings, structural elementsthat have substantially the same function and structure are denoted withthe same reference numerals, and repeated explanation of thesestructural elements is omitted.

Incidentally, the description is made in the following order.

-   1. First Embodiment (Light Source Unit Including Two Dichroic    Mirrors)-   1.1. Configuration of Display Device-   1.2. Configuration of Light Source Unit-   2. Second Embodiment (Light Source Unit Including One Dichroic    Mirror)    <1. First Embodiment>    [1.1. Configuration of Display Device]

First, referring to FIG. 1, one exemplary configuration of a displaydevice 1 including a light source unit 100 according to a firstembodiment of the present disclosure is described. FIG. 1 is a schematicconfiguration diagram illustrating one exemplary configuration of thedisplay device 1 including the light source unit 100 according to theembodiment.

The display device 1 according to the embodiment represents oneexemplary configuration of a projector for collecting light from a lightsource which emits the light, emitting the light from a projection lensthrough a device causing display of an image, and projecting the imageon a display plane such as a screen S. The display device 1 illustratedin FIG. 1 is one exemplary configuration of a projector using 3 LCDs asmicrodisplays.

Light emitted from the light source unit 100 passes through anintegrator lens 2 constituted of a first lens array 2 a and a secondlens array 2 b in order to maintain its brightness still at the edges ofthe display image, after that, passes through a polarization conversionelement 3 a and a condenser lens 3 b, and is separated into componentsfor individual wavelength regions.

The light having passed through the condenser lens 3 b is incident on afirst reflection dichroic mirror 4 a reflecting only the light in thered wavelength region and allowing the light in the other wavelengthregions to pass through. Thereby, the light in the red wavelength regionis reflected by the first reflection dichroic mirror 4 a and proceedstoward a reflection mirror 5 a. The light in the red wavelength regionis further reflected by the reflection mirror 5 a and is incident on ared liquid crystal panel 6 a.

The light in the other wavelength regions having passed through thefirst reflection dichroic mirror 4 a is incident on a second reflectiondichroic mirror 4 b. The second reflection dichroic mirror 4 b reflectsonly the light in the green wavelength region and allows the light inthe other wavelength region, that is, the light in the blue wavelengthregion to pass through. The light in the green wavelength regionreflected by the second reflection dichroic mirror 4 b is incident on agreen liquid crystal panel 6 b. Moreover, the light in the bluewavelength region having passed through the second reflection dichroicmirror 4 b is reflected by reflection mirrors 5 b and 5 c, and afterthat, is incident on a blue liquid crystal panel 6 c.

Each of the liquid crystal panels 6 a to 6 c for the individual colorsmodulates the light incident on each of those according to an inputimage signal, and generates signal light of the image corresponding toeach of R, G and B. For the liquid crystal panels 6 a to 6 c, forexample, transmissive liquid crystal elements using high temperaturepolysilicon TFTs may be employed. The signal light obtained by themodulation with each of the liquid crystal panels 6 a to 6 c is allowedto be incident on a dichroic prism 7 and the individual componentsthereof are combined with one another. The dichroic prism 7 is formedinto a rectangular solid with four triangular prisms to reflect the redsignal light and the blue signal light but to allow the green signallight to pass through. The signal light for the colors obtained by thecombining with the dichroic prism 7 is incident on a projection lens 8to be projected on the display plane of the screen S or the like as animage.

In the display device 1, the liquid crystal panels 6 a to 6 c and thedichroic prism 7 function as a light modulating/combining system formodulating and combining the incident light. Moreover, the integratorlens 2, the polarization conversion element 3 a, the condenser lens 3 b,the reflection dichroic mirrors 4 a and 4 b and the reflection mirrors 5a to 5 c function as an illumination optical system for guiding thelight from the light source unit 100 to the liquid crystal panels 6 a to6 c constituting the light modulating/combining system. Furthermore, theprojection lens 8 functions as a projection optical system forprojecting the image emitted from the dichroic prism 7.

[1.2. Configuration of Light Source Unit]

As the light source unit 100 of such a display device 1, in the presenttechnology, a light source device is employed in which a solid-statelight source irradiates a fluorescent material with light and theresulting fluorescent emission light is utilized. Few fluorescentmaterials are excellent in heat durability and light stability in termsof light emission efficiency and some suffer luminance saturation andtemperature quenching to cause a decrease of the fluorescent lightemission efficiency. For example, since SCASN-based or CASN-basedfluorescent materials with the emission spectra of the primary colorsillustrated in FIG. 13 rapidly cause luminance saturation andtemperature quenching, a bright light source is difficult to beattained. Namely, the fluorescent material irradiated with strong lightfrom a laser or the like causes a decrease of the fluorescent lightemission efficiency, but a less irradiation amount of the light causes aless fluorescent emission light intensity in turn, this leading to thelight emitted from the light source unit 100 to be less bright.

A YAG-based fluorescent material is a fluorescent material that hardlycauses luminance saturation and temperature quenching and can attain alight source to be bright. FIG. 2 illustrates representative emissionspectra for the YAG-based fluorescent material. Irradiation light(exciting light) of the YAG-based fluorescent material typically employsblue light and the blue light and fluorescent emission light of theYAG-based fluorescent material can be used for the light source. Namely,the emission spectrum (solid line) in the blue wavelength regionillustrated in FIG. 2 is the emission spectrum of the irradiation lightand the emission spectrum (dot and dash line) in the green wavelengthregion is the emission spectrum attributable to the fluorescent emissionlight of the YAG-based fluorescent material. Compared with the idealemission spectra illustrated in FIG. 12, the emission spectraillustrated in FIG. 2 are weak as to the light in the red wavelengthregion and present imbalance for the three primary colors. Presentingwhite based on these emission spectra causes white considerably close topale blue to be presented.

In consideration of the above, the light source unit 100 according tothe embodiment is configured to supplement the emission spectra for thefluorescent material with light in a wavelength region of the colorlacking therein to be close to the ideal emission spectra illustrated inFIG. 12. FIG. 3 illustrates a configuration of the light source unit 100according to the embodiment. The light source unit 100 illustrated inFIG. 3 is a light source device using a reflection-type fluorescentmaterial.

As illustrated in FIG. 3, the light source unit 100 according to theembodiment includes a first light source 112 and a second light source114 as light sources. The first light source 112 is a light source forirradiating (for exciting) a fluorescent material and may employ, forexample, a laser. The first light source 112 allows a fluorescentmaterial which is a wavelength conversion unit to emit light efficientlyand employs a laser with the blue wavelength region (approximately 420to 500 nm) in the embodiment. The second light source 114 emits light ina wavelength region of the color lacking in the first light source 112and in the fluorescent emission light with the fluorescent material.Since the first light source 112 employs a laser with the bluewavelength region and the fluorescent material employs a YAG-basedfluorescent material in the embodiment, the light with the wavelengthspectra as illustrated in FIG. 2 is obtained. The light is weak in thered wavelength region (approximately 610 to 700 nm), and therefore, thesecond light source 114 according to the embodiment is configured, forexample, of a laser emitting light in the red wavelength region asillustrated in FIG. 4.

Light emitted from the first light source 112 is allowed to be light intwo wavelength regions with a first dichroic mirror 120, a lens 130 anda fluorescent material 140 which is provided in a rotation wheel unit150, these constituting the light source unit 100. The lens 130 isdisposed on the same optical path as that of first light source 112 andthe first dichroic mirror 120 is disposed between the first light source112 and the lens 130. The first dichroic mirror 120 is provided, forexample, to incline by approximately 45° relative to the optical pathbetween the first light source 112 and the lens 130. Moreover, thefluorescent material 140 is disposed such that the lens 130 collects thelight on the fluorescent material 140. Here, the lens 130 is desirableto collect the light on the circumferential part of a wheel 152 ratherthan the vicinity of the center thereof in order to enhance coolingperformance of the wheel 152 as mentioned later.

The light emitted from the first light source 112 is incident on a firstplane 120 a of the first dichroic mirror 120. The first dichroic mirror120 allows the light of the first light source 112 incident on the firstplane 120 a to pass through. Moreover, the first dichroic mirror 120reflects, on a second plane 120 b, the reflected light led from thefirst light source 112 and fluorescent emission light from thefluorescent material 140 which is disposed opposite to the first lightsource 112 via the first dichroic mirror 120 and the lens 130. The lightemitted from the first light source 112 passes through the firstdichroic mirror 120 and is collected with the lens 130 for irradiationof the fluorescent material 140.

The fluorescent material 140 is a YAG-based fluorescent material. Uponirradiation with the light in the blue wavelength region from the firstlight source 112, it absorbs the light and emits light in a differentwavelength region from the blue wavelength region. The fluorescentmaterial 140 is applied, for example, on the wheel 152 in a disc shapewhich is made of metal such as aluminum as illustrated in FIG. 3. Thefluorescent material 140 may be applied on the entire surface of thewheel 152 or only on the circumferential part thereof.

The wheel 152 is rotated by a driving unit 156 such as a motor about arotation shaft 154 which is the rotation center and provided at thecenter of the wheel 152, constituting the rotation wheel unit 150. Thisis a mechanism for preventing the wheel 152 from holding the heat due tothe irradiation with the light, and thus, causing a decrease of thelight emission efficiency of the fluorescent material 140 and preventinga melt of a resin used for adhesion of the fluorescent material 140 withthe wheel 152. The rotation of the wheel 152 with the rotation wheelunit 150 to rotate the fluorescent material 140 can enhance coolingperformance of the wheel 152 and improve light emission efficiency ofthe fluorescent material 140.

The fluorescent emission light emitted from the fluorescent material 140is, for example, light in the green wavelength region and passes throughthe lens 130 along with the light in the blue wavelength region which isnot absorbed by the fluorescent material 140 and is reflected on thewheel 152 to be incident on the second plane 120 b of the first dichroicmirror 120. Here, the light in the blue wavelength region which isreflected on the surface of the wheel 152 can be efficiently reflectedby the first dichroic mirror 120 when a function of rotating orscrambling polarized light is provided. The first dichroic mirror 120reflects the fluorescent emission light and the reflected light whichare incident on the second plane 120 b toward a second dichroic mirror180.

Meanwhile, the light emitted from the second light source 114 isincident on the second dichroic mirror 180 via a diffusion lens 160 anda lens 170 which constitute the light source unit 100. The diffusionlens 160 and the lens 170 are disposed sequentially on the same opticalpath as that of the second light source 114 and the second dichroicmirror 180 is disposed on the path beyond them. The reflected light onthe first dichroic mirror 120 is also incident on the second dichroicmirror 180, therefore, which is provided at the position where theincident direction of the reflected light crosses the optical path ofthe second light source 114, the diffusion lens 160 and the lens 170.The second dichroic mirror 180 is provided, for example, to besubstantially parallel to the first dichroic mirror 120 and to inclineby approximately 45° relative to the optical path of the second lightsource 114, the diffusion lens 160 and the lens 170.

The second dichroic mirror 180 allows the fluorescent emission light andthe reflected light which are reflected by the first dichroic mirror 120and incident on the first plane 180 a to pass through and reflects thelight of the second light source 114 which is incident on the secondplane 180 b. Namely, the second dichroic mirror 180 functions as afilter having characteristics in which light in a specific wavelengthregion to be combined is reflected and light in the other wavelengthregions is allowed to pass through. The second dichroic mirror 180 isconfigured, for example, to have characteristics of a notch filter asillustrated in FIG. 5. Thereby, it reflects only the light in thewavelength region which is led from the second light source 114 andincident on the second plane 180 b as illustrated in FIG. 4.

The second dichroic mirror 180 is configured to limit the reflectedlight to a part thereof corresponding to the wavelength region of thesecond light source 114 for supplementation. Narrowing the wavelengthregion to be filtered with the second dichroic mirror 180 allows thelight in the red wavelength region which is contained in the fluorescentemission light with the fluorescent material 140 out of the lightincident from the first dichroic mirror 120 to be reflected to as lessan extent as possible. The second light source 114 for supplementationwith the light in the red wavelength region according to the embodimentis typically weak in output and the second light source 114 can beinsufficient for the supplementation. Therefore, in order to use thelight in the red wavelength region contained in the fluorescent emissionlight effectively, the second dichroic mirror 180 is configured to be anarrow band filter such as a notch filter.

Thus, the second dichroic mirror 180 combines the light in the redwavelength region led from the second light source 114 onto the emittedlight led from the first light source 112 constituted of the fluorescentemission light and the reflected light. The resulting light haswavelength spectra, for example, as illustrated in FIG. 6 eventually.The emission spectrum (broken line) for the red wavelength region inFIG. 6 is attributable to the light from the second light source 114. Asabove, according to the light source unit 100 according to theembodiment, the light led from the first light source 112 and thefluorescent emission light with the fluorescent material 140, which havea deficiency in their emission spectra, can be effectively supplementedwith the light in the red wavelength region using the second lightsource 114.

Moreover, as in the light source unit 100 according to the embodiment,employing a laser as the second light source 114 for supplementationnarrows the width of the emission spectrum. Thereby, the light in thered wavelength region contained in the fluorescent emission light can becut to as less an extent as possible and the cut light in the redwavelength region can be supplemented by the second light source 114.

<2. Second Embodiment>

Next, based on FIG. 7 and FIG. 8, one exemplary configuration of a lightsource unit 200 according to a second embodiment of the presentdisclosure is described. FIG. 7 is a schematic configuration diagramillustrating one exemplary configuration of the light source unit 200according to the embodiment. FIG. 8 is an explanatory drawingillustrating one example of characteristics of a dichroic mirror 220according to the embodiment. In FIG. 7, the constituents same as thoseof the light source unit 100 according to the first embodiment are givenwith the same signs and the detailed description for those is omitted.

As in the first embodiment, the light source unit 200 according to theembodiment is provided as a light source unit, for example, for thedisplay device 1 illustrated in FIG. 1. The light source unit 200 isdifferent in the first dichroic mirror 120 which reflects thefluorescent emission light with the fluorescent material and also hasthe characteristics of the second dichroic mirror 180 functioning as afilter for combination to be integrated into one compared with the lightsource unit 100 according to the first embodiment. Thereby, the numberof constituent components can be made less and not only the light sourceunit 200 but also the display device 1 are attained to be small, thisenabling costs to be reduced.

As illustrated in FIG. 7, the light source unit 200 includes the firstlight source 112 and the second light source 114 as light sourcessimilarly to the light source unit 100 according to the firstembodiment. The first light source 112 is a light source for irradiating(for exciting) a fluorescent material and may employ, for example, alaser. The first light source 112 allows a fluorescent material to emitlight efficiently and employs a laser with the blue wavelength regionalso in the embodiment. The second light source 114 emits light in awavelength region of the color lacking in the first light source 112 andin the fluorescent emission light with the fluorescent material. Also inthe embodiment, since the first light source 112 employs a laser withthe blue wavelength region and the fluorescent material employs aYAG-based fluorescent material similarly to the first embodiment, thelight is weak in the red wavelength region, and therefore, the secondlight source 114 according to the embodiment is also configured, forexample, of a laser emitting light in the red wavelength region asillustrated in FIG. 4.

Light emitted from the first light source 112 is allowed to be light intwo wavelength regions with the dichroic mirror 220, the lens 130 andthe fluorescent material 140 which is provided in the rotation wheelunit 150, these constituting the light source unit 200. The lens 130 isdisposed on the same optical path as that of the first light source 112and the dichroic mirror 220 is disposed between the first light source112 and the lens 130. Moreover, the fluorescent material 140 is disposedsuch that the lens 130 collects the light on the fluorescent material140. Here, the lens 130 is desirable to collect the light on thecircumferential part of the wheel 152 rather than the vicinity of thecenter thereof in order to enhance cooling performance of the wheel 152similarly to the first embodiment.

Since the light from the second light source 114 is also incident on thedichroic mirror 220, the dichroic mirror 220 is provided at the positionwhere the incident direction of the incident light crosses the opticalpath between the first light source 112 and the lens 130. The dichroicmirror 220 is provided, for example, to incline by approximately 45°relative to the optical path between the first light source 112 and thelens 130 and the incident direction from the second light source 114.

The dichroic mirror 220 allows the light of the first light source 112incident on a first plane 220 a to pass through. Furthermore, thedichroic mirror 220 also allows the light which is led from the secondlight source 114 and incident on the first plane 220 a to pass through.Moreover, the dichroic mirror 220 reflects, on a second plane 220 b, thereflected light led from the first light source 112 and the fluorescentemission light from the fluorescent material 140 which is disposedopposite to the first light source 112 via the dichroic mirror 220 andthe lens 130. Namely, as illustrated in FIG. 8, the dichroic mirror 220is configured to have characteristics in which the light in the bluewavelength region and the red wavelength region is allowed to passthrough and the light in the other wavelength regions such as the greenwavelength region not to pass through.

The light emitted from the first light source 112 passes through thedichroic mirror 220 and is collected with the lens 130 for irradiationof the fluorescent material 140. The fluorescent material 140 is aYAG-based fluorescent material. Upon irradiation with the light in theblue wavelength region from the first light source 112, it absorbs thelight and emits light in a different wavelength region from the bluewavelength region. The fluorescent material 140 may be provided on thewheel 152 of the rotation wheel unit 150 to be rotated in order toenhance cooling performance and improve light emission efficiency.

The fluorescent emission light emitted from the fluorescent material 140is, for example, light in the green wavelength region and passes throughthe lens 130 along with the light in the blue wavelength region which isnot absorbed by the fluorescent material 140 and is reflected on thewheel 152 to be incident on the second plane 220 b of the dichroicmirror 220. The dichroic mirror 220 reflects the fluorescent emissionlight and the reflected light which are incident on the second plane 220b in the emission direction of the light of the light source unit 200.

Meanwhile, the second light source 114 is disposed, relative to thefirst light source 112, such that the emission directions of the lightof these are substantially normal to each other. The light emitted fromthe second light source 114 is incident on the first plane 220 a of thedichroic mirror 220. The first plane 220 a of the dichroic mirror 220also allows the light in the wavelength region for the second lightsource 114 to pass through. Accordingly, the light from the second lightsource 114 passes through the dichroic mirror 220 still to proceed inthe emission direction of the light of the light source unit 200.

Thus, the dichroic mirror 220 combines the light in the red wavelengthregion led from the second light source 114 onto the emitted light ledfrom the first light source 112 constituted of the fluorescent emissionlight and the reflected light. The resulting light has wavelengthspectra, for example, as illustrated in FIG. 6 eventually. According tosuch a configuration of the light source unit 200, the light led fromthe first light source 112 and the fluorescent emission light led fromthe fluorescent material 140, which have a deficiency in the emissionspectra, can be effectively supplemented with the light in thewavelength region of the deficiency using the second light source 114.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

For example, in the above-mentioned embodiments, a projector with 3 LCDsas illustrated in FIG. 1 is exemplarily presented as the display device1 to which the light source unit 100 or 200 is applied, whereas thepresent technology is not limited to such examples. The system of thedisplay device 1 to which the light source unit 100 or 200 is applied isnot limited particularly but a DLP system or a LCOS system may beapplied to the display device, for example.

Moreover, in the above-mentioned embodiments, the first light source 112is a light source for obtaining light in a specific wavelength region(blue wavelength region in the above-mentioned embodiments) and lightfor irradiation of a fluorescent material, whereas the presenttechnology is not limited to such examples. For example, the light in aspecific wavelength region and the light for irradiation of afluorescent material may be obtained by different light sources. Forexample, the configuration of the light source unit 100 illustrated inFIG. 3 employs the first light source 112 for the light for irradiationof a fluorescent material. Another light source for the blue wavelengthregion to obtain the light in the blue wavelength region is providedsuch that its incident direction of the light is substantially normal tothat of the first light source 112 and its light is incident on thefirst plane 120 a of the first dichroic mirror 120. Namely, the lightsource for the blue wavelength region is provided such that its opticalaxis coincides with the emission direction of the light of the lightsource unit 110. Such a configuration can attain the similar effects tothose in the above-mentioned embodiments.

Furthermore, in the above-mentioned embodiments, the first light source112 and the second light source 114 employ lasers, whereas the presenttechnology is not limited to such examples. For example, they only haveto be solid-state light sources such as LEDs. A laser is suitable forapplication to the light source units 100 and 200 according to anembodiment of the present technology, having straightness.

Moreover, the present technology is not limited to the configurations ofthe light source units 100 and 200 according to the above-mentionedembodiments illustrated in FIG. 3 and FIG. 7. The optical systems can beproperly changed to be arranged, and correspondingly, characteristics ofthe optical systems may be changed. For example, the second dichroicmirror 180 has the characteristics in which the light in a specificwavelength region (red wavelength region) to be combined is reflectedand the light in the other wavelength regions is allowed to pass throughin the above-mentioned first embodiment. Alternatively, it may havecharacteristics in which the light in a specific wavelength region (redwavelength region) to be combined is allowed to pass through and thelight in the other wavelength regions is reflected according to theincident direction and the emission direction of the light of the secondlight source 114. In addition, the light source units 100 and 200 aredesirable to be disposed such that the light beams in the bluewavelength region, the green wavelength region and the red wavelengthregion are overlapped in the emission direction of the light of thelight source units 100 and 200 to have the same optical axis, and afterthat, to be emitted.

Furthermore, for the above-mentioned embodiments, the description ismade, supposing that the second light source 114 which emits the lightin the red wavelength region for the light source units 100 and 200 isprovided directly on bases of the light source units 100 and 200,whereas the present technology is not limited to such examples. Thewavelength region of the laser emitting the light in the red wavelengthregion is liable to change depending on its usage temperature. Hence,the second dichroic mirror 180 according to the first embodiment whichis configured, for example, as a narrow band filter which reflects thelight in the red wavelength region can cause a shift of the wavelengthregion of the second light source 114, this causing a displacement fromthe wavelength region of reflection on the second dichroic mirror 180.In turn, a proper supplementation with the light in the wavelengthregion for the second light source 114 is not attained, this causingimbalance for the color gamut.

Therefore, for example, the second light source 114 may be provided onthe base via a temperature keeping mechanism configured of a Peltierelement and the like to keep the usage temperature of the second lightsource 114 constant, and thus, to maintain the wavelength region of thelight of the light source 114. Thereby, variation of the wavelengthregion of the light of the second light source 114 can be reducedregardless of an environment of usage. Moreover, still when variation inproduction of the second dichroic mirrors 180 causes a displacement ofthe wavelength region of the reflection from the wavelength region ofthe light of the second light source 114, the wavelength region of thelight of the second light source 114 can be allowed to meet thecharacteristics of the second dichroic mirror 180.

Additionally, the present technology may also be configured as below.

(1) A light source device including:

a first light source configured to emit light in a first wavelengthregion;

a second light source configured to emit light in a second wavelengthregion different from the first wavelength region;

a wavelength conversion unit including a fluorescent material andconfigured to emit fluorescent emission light in a different wavelengthregion upon irradiation with the light in the first wavelength region;and

a combining unit that has wavelength selectivity to a specificwavelength region corresponding to the second wavelength region andcombines the light in the first wavelength region from the first lightsource, the light in the second wavelength region from the second lightsource, and the fluorescent emission light which are incident on thecombining unit with one another.

(2) The light source device according to (1),

wherein the light in the first wavelength region, the light in thesecond wavelength region, and the fluorescent emission light arecombined with one another on a same axis.

(3) The light source device according to (1) or (2),

wherein the wavelength conversion unit is provided to be rotatable on aplane which crosses an incident direction of the light of the firstlight source.

(4) The light source device according to any one of (1) to (3),

wherein the first wavelength region is a blue wavelength region.

(5) The light source device according to any one of (1) to (4),

wherein the second wavelength region is a red wavelength region.

(6) The light source device according to any one of (1) to (5),

wherein at least any one of the first light source and the second lightsource is a laser diode.

(7) The light source device according to any one of (1) to (6), furtherincluding:

a fluorescent light reflection unit that is provided between the firstlight source and the wavelength conversion unit, allows the light in thefirst wavelength region to pass through and reflects the fluorescentemission light toward the combining unit.

(8) A light source device including:

a first light source configured to emit light in a first wavelengthregion;

a second light source configured to emit light in a second wavelengthregion different from the first wavelength region;

a wavelength conversion unit including a fluorescent material andconfigured to emit fluorescent emission light in a different wavelengthregion upon irradiation with the light in the first wavelength region;and

a combining unit that has wavelength selectivity to a specificwavelength region corresponding to the first wavelength region and thesecond wavelength region and combines the light in the first wavelengthregion from the first light source, the light in the second wavelengthregion from the second light source and the fluorescent emission lightwhich are incident on the combining unit with one another.

(9) A display device including:

a light source unit;

a light modulating/combining system configured to modulate and combineincident light;

an illumination optical system configured to guide light emitted fromthe light source unit to the light modulating/combining system; and

a projection optical system configured to perform projection of an imageemitted from the light modulating/combining system,

wherein the light source unit includes

a first light source configured to emit light in a first wavelengthregion,

a second light source configured to emit light in a second wavelengthregion different from the first wavelength region,

a wavelength conversion unit including a fluorescent material andconfigured to emit fluorescent emission light in a different wavelengthregion upon irradiation with the light in the first wavelength region,and

a combining unit that has wavelength selectivity to a specificwavelength region corresponding to the second wavelength region andcombines the light in the first wavelength region from the first lightsource, the light in the second wavelength region from the second lightsource, and the fluorescent emission light which are incident on thecombining unit with one another.

(10) A display device including:

a light source unit;

a light modulating/combining system configured to modulate and combineincident light;

an illumination optical system configured to guide light emitted fromthe light source unit to the light modulating/combining system; and

a projection optical system configured to perform projection of an imageemitted from the light modulating/combining system,

wherein the light source unit includes

a first light source configured to emit light in a first wavelengthregion,

a second light source configured to emit light in a second wavelengthregion different from the first wavelength region,

a wavelength conversion unit including a fluorescent material andconfigured to emit fluorescent emission light in a different wavelengthregion upon irradiation with the light in the first wavelength region,and

a combining unit that has wavelength selectivity to a specificwavelength region corresponding to the first wavelength region and thesecond wavelength region and combines the light in the first wavelengthregion from the first light source, the light in the second wavelengthregion from the second light source, and the fluorescent emission lightwhich are incident on the combining unit with one another.

What is claimed is:
 1. A light source device, comprising: a first lightsource configured to emit a first light; a second light sourceconfigured to emit a second light different from the first light; aconversion unit that includes a fluorescent material, wherein theconversion unit is configured to emit fluorescent emission light uponirradiation with the first light; a first fluorescent light reflectionunit configured to reflect the fluorescent emission light; and a secondfluorescent light reflection unit configured to: pass the fluorescentemission light reflected from the first fluorescent light reflectionunit; filter a part of the passed fluorescent emission light to emitfiltered fluorescent emission light; and combine the second light ontothe first light and the filtered fluorescent emission light.
 2. Thelight source device according to claim 1, wherein the first light has afirst wavelength region, and wherein the second light has a secondwavelength region.
 3. The light source device according to claim 1,wherein the second fluorescent light reflection unit is furtherconfigured to combine the first light, the second light, and thefiltered fluorescent emission light on a same axis.
 4. The light sourcedevice according to claim 1, wherein the conversion unit is furtherconfigured to rotate on a plane which crosses an incident direction ofthe first light.
 5. The light source device according to claim 1,wherein the first light is a blue wavelength region.
 6. The light sourcedevice according to claim 1, wherein the second light is a redwavelength region.
 7. The light source device according to claim 1,wherein at least one of the first light source or the second lightsource is a laser diode.
 8. The light source device according to claim1, wherein the first fluorescent light reflection unit is between thefirst light source and the conversion unit, wherein the firstfluorescent light reflection unit is further configured to: pass thefirst light; and reflect the fluorescent emission light toward thesecond fluorescent light reflection unit.
 9. The light source deviceaccording to claim 2, wherein the second fluorescent light reflectionunit has wavelength selectivity to a specific wavelength regioncorresponding to the second wavelength region.
 10. The light sourcedevice according to claim 1, wherein the conversion unit is furtherconfigured to rotate on a plane which crosses an incident direction ofthe first light.
 11. The light source device according to claim 1,wherein the first fluorescent light reflection unit is between the firstlight source and the conversion unit.
 12. The light source deviceaccording to claim 11, wherein the first fluorescent light reflectionunit is configured to pass the first light.
 13. The light source deviceaccording to claim 11, wherein the second fluorescent light reflectionunit is different from the first fluorescent light reflection unit. 14.The light source device according to claim 13, wherein the secondfluorescent light reflection unit is further configured to: pass thefirst light; and reflect the second light.
 15. A light source device,comprising: a first light source configured to emit a first light; asecond light source configured to emit a second light different from thefirst light; a conversion unit having a fluorescent material, whereinthe conversion unit is configured to emit fluorescent emission lightupon irradiation with the first light; a first fluorescent lightreflection unit configured to reflect the fluorescent emission light;and a second fluorescent light reflection unit configured to: pass thefluorescent emission light reflected from the first fluorescent lightreflection unit; filter a part of the passed fluorescent emission lightto emit filtered fluorescent emission light; and combine the secondlight onto the first light and the filtered fluorescent emission light.16. A display device, comprising: a light source unit configured to emitlight; a light modulating/combining system configured to: modulateincident light; combine the modulated incident light; and output animage based on the combined modulated incident light; an illuminationoptical system configured to guide the light emitted from the lightsource unit to the light modulating/combining system; and a projectionoptical system configured to project the image output from the lightmodulating/combining system, wherein the light source unit includes: afirst light source configured to emit a first light, a second lightsource configured to emit a second light different from the first light;a conversion unit having a fluorescent material, wherein the conversionunit is configured to emit fluorescent emission light upon irradiationwith the first light; a first fluorescent light reflection unitconfigured to reflect the fluorescent emission light; and a secondfluorescent light reflection unit configured to: pass the fluorescentemission light reflected from the first fluorescent light reflectionunit; filter a part of the passed fluorescent emission light to emitfiltered fluorescent emission light; and combine the second light ontothe first light and the filtered fluorescent emission light.